Apple’s iPhone X has been the “most highly-anticipated” version of the technology giant’s flagship phone, the chief executive of AT&T Communications, told CNBC on Tuesday.

John Donovan, who is the boss of the second-largest U.S. mobile carrier, answered in the affirmative when asked by CNBC if sales of this iPhone would be “bumper”.

“All the signs are that customers love it. It’s probably the most highly-anticipated version… and demand has been strong. So we’re pleased,” Donovan said in a TV interview at the Web Summit technology conference in Lisbon, Portugal.

Apple’s tenth anniversary edition iPhone X began shipping Friday. It starts at $999 and has been praised in numerous reviews.

Chief Executive Tim Cook told CNBC in a recent interview that “customer demand is off the charts.” Several analysts have also backed up the view.

There appears to be pent up demand. Analysts at GHB Insights estimate that over 350 million iPhone users have phones that are two years old or older. These people could be looking to upgrade to the new iPhone X or iPhone 8 models.

But the technology giant has also faced problems including delays in production that has resulted in people having to wait several weeks for an iPhone X.